1. Field of the Invention
The present invention relates to mechanical presses, and, more particularly, to a variable slide motion adjustment apparatus and method for changing the motion versus crankshaft angle curve of the press slide.
2. Description of the Related Art
Mechanical presses, for example, stamping presses and drawing presses, comprise a frame having a crown and bed. A slide is supported within a frame for motion toward and away from the bed. The slide is driven by a crankshaft having a connecting arm connected to the slide.
Such mechanical presses are widely used for stamping and drawing operations and vary substantially in size and available tonnage depending upon the intent of use.
After manufacturing of a mechanical press, the only way to change the slide motion or the usual slider crank motion of the slide, was to substitute new parts and particular sizes and gearing of the press. Additionally, a necessity was the use of a wrench or other hand tools to change particular settings on the apparatus thereof. A benefit in some types of press room operations would be the ability to change the slider crank motion to vary the speed and dwelling of the slide without such manual adjustments.
Of interest, in some mechanical presses, is that there are portions of the slide which may be actuated by a hydraulic cylinder hydraulic pressure in the same rectilinear direction as slide movement, so therefore the bottom of the slide may be controlled in an additional upward or downward direction during slide reciprocation. Such structure necessitates additional parts such as the hydraulic cylinders or hydraulic pressure application means, along with the various plumbing and controls that necessarily reciprocate with the slide. Such additional mass on the slide may cause problems in press balance during operation.
What is needed in the art is the ability to mechanically alter the slider crank motion of the slide without the use of wrenched or hand tools to maintain mechanical connections between all of the moving parts.
The present invention is directed to improve mechanical press slide motion control by creating an apparatus and method for allowing mechanical control of the slide motion versus crankshaft angle curve, thereby altering the speed position and dwell of the slide during operation.
The present invention provides an infinite variable slide motion control apparatus utilizing a differential disposed between the driveshaft and connection arms of the slide. Such a differential is controlled or adjusted by links connecting such differential to other operating gears. By varying positions of the links connected to the differential and their particular orientation relative to the gearing, the effective link length is adjusted, thereby changing the type of slide motion. Changes in slide motion may be used to obtain the best performance of a particular die used in production with the workpieces on the press. Such effective link length adjustment is controlled by use of a hydraulic motor within an encoder giving a pulse count of the position of the link being adjusted. By determining the effective location of the link to the associated gearing and differential control of the press slide, an effective press slide curve is created.
The invention, in one form thereof, comprises a mechanical press including a frame and bed connected together with a slide connected with the frame for reciprocating motion opposing the bed. In the preferred embodiment, the clutch is still engaged as conventionally utilized in the flywheel with the energy from the flywheel being transmitted to the slide through a driveshaft, main gears through a controlled differential to a crankshaft and slide connection arms. Differential mechanism operation is controlled via the position of a link and link spider arrangement connected either to the main gear of a press or to an auxiliary drive gear.
The invention, in another form thereof, includes a hydraulic cylinder, screw adjustment or other means to vary the effective position and/or length of a link or link spider connected to one of the main gear or drive gear of the press. Such changes in relative position of the link can cause the differential in a particular application, to control motion of the other operating portions of the press.
An advantage of the infinite variable slide motion system of the present invention is that now mechanical presses may control the motion versus crankshaft angle curve, with variable alternate slide motion curves as needed for particular press or drawing operations. Of particular interest is the ability to mechanically change the dwell of the press slide to maintain it for particular periods of time and crankshaft or driveshaft rotation.
Another advantage of the present invention is the ability to utilize a differential between the main gear and eccentric portions of the crankshaft, thereby obtaining particular control of the power applied thereto.
A further advantage of the invention is the ability to create a slide motion different from the normal slider crank motion to increase the dwell of the slide on the bottom for upwards of 25xc2x0xc2x115xc2x0.
Yet another advantage of the present invention is the ability of the clutch to maintain fully engaged and transfer energy therefrom to the crankshaft and slide via entire mechanical connections.
Another advantage of the present invention is that the infinite variable slide motion may be adjusted without a wrench or hand tool, but by use of a hydraulic motor controlling the effective position or length of the control links utilized.
Yet another advantage of the present invention is that the system now allows dies and tooling to tap or draw at 90xc2x0 from the bed during the vastly extended slide dwell period.
Still another advantage of the present invention is the creation of a substantially constant slide and die velocity during the bottom 25 percent of slide stroke.
A further advantage of the present invention is the ability to withstand overload hits without breaking the links between the slide and crankshaft. Stamping presses may take tremendous overload due to items left in the presses, and for other reasons. A conventional press with crankshaft connection slide can withstand such load, but presses with links between the crankshaft and slide for adjusting stroke have had trouble withstanding such severe overloads.
Another advantage of the present invention is on a high speed press a dynamic balancer may be adjusted at the same time as the slide motion is adjusted.